[Question] How can I find trustworthy dietary advice?

I currently think that the official dietary advice is sometimes untrustworthy, and I don’t know when it’s trustworthy and when it isn’t, so I’m in a state of epistemic learned helplessness. Some reasons why I think this:

--I get the impression that much of the official advice of the past was actively harmful; the official advice has flip-flopped on many things over the past decades; things which were touted as healthy were later shown to be unhealthy, and vice versa. So presumably some of the current official advice is also actively harmful, and some of it is merely useless. But I don’t know which.

--I get the impression that there are studies available supporting pretty much any conclusion; if I want to believe that red meat is bad for me, I can find mountains of studies showing that it is bad for me, and if I want to believe that it is good for me, I can go talk to carnivore diet people and they’ll give me convincing evidence it’s actually really good for me.

I’m optimistic that if I spent a few weeks of effort looking into the literature and reading the studies myself I could come to good opinions on this topic. But maybe someone here has already done this? Or maybe I’m just wrong about the official dietary advice?